Amazon has concluded a six-month field trial of a new type of rooftop heat pump at its Houston, Texas, logistics facility. The dedicated outdoor air system (DOAS) engineered by Massachusetts-based Transaera incorporates a type of HVAC technology that treats only outdoor air for ventilation, handling it independently from a building’s main heating and cooling system.

Designed to provide cooling, heating and dehumidification in a single integrated platform, the system operates as an all-electric heat pump, eliminating the need for gas-fired reheat while addressing both sensible and latent loads in commercial buildings. The main attraction for Amazon is the ability of the DOAS to cool the facility using 40% less energy relative to conventional HVAC options.

Key to the DOAS performance is a desiccant that coats a six-foot wheel that slowly spins inside each of its units. Based on metal-organic frameworks, the desiccant material removes moisture from incoming air before the cooling stage, altering the air-treatment sequence. The result: moisture is removed first and cooling is applied afterward, a sequence expected to improve system efficiency compared to conventional approaches.

As air passes into the unit, the desiccant draws moisture out of the air, which then passes through a heat exchanger before being dispersed into the building. Stale air is drawn out of the building along with heat from the heat exchanger, which flows through the moisture-saturated wheel. The heat from that air releases the moisture from the desiccant so it can be exhausted outside.

Amazon said Transaera’s DOAS units will help the company reduce its energy use and help it on its path toward net-zero carbon emissions by 2040.